Comment 30 for bug 1701499

Yea, I think it's related to gnome-shell.

Piotr, can you enable persistent journal for journald?

$ sudo -s
# mkdir -p /var/log/journal
# systemd-tmpfiles --create --prefix /var/log/journal
# systemctl restart systemd-journald

If your computer freeze again, you can use
$ journalctl -b -1
to check the log from last boot. Check if you can see some warning about gnome-shell.